The Metabolic and Cardiac Effects of exercise in the Elderly Project represents the collaborative efforts of several Departments and Schools at the University of Washington to conduct a broad-based research program to define the metabolic and cardiovascular consequences of aerobic exercise training in the elderly with the hypothesis that training in the elderly will have a positive impact on the physiological parameters we have defined. The program project includes a core and four projects. The core will recruit and train the subjects, maintain and analyze the project data, oversee the implementation of the research activities, and promote relevant new research programs in areas related to the project. The four projects will address the following general issues in healthy young and elderly subjects: 1) The cardiovascular changes which occur with training and the adrenergic mechanisms which may be responsible for the adaptations that occur; 2) The effects of training on sympathetic nervous system activity, energy expenditure, and body composition; 3) The effects of training on adrenergic responsiveness as defined by adrenergic receptor function and adenylate cyclase activity; 4) The effects of training on carbohydrate metabolism and insulin sensitivity and release. The individual projects will be tied together not only by the Core activities but also by correlation of data between the different projects, e.g., the relationship between lymphocyte and platelet adrenergic receptor mechanisms and cardiovascular adrenergic responsiveness; the relationship between insulin sensitivity and both sympathetic activity, and body composition; and the correlation of adipose tissue adrenergic receptor mechanisms to body composition and fat distribution. We hypothesize that: 1) After participation in a 6 month aerobic exercise program both young and elderly subjects will demonstrate significant improvements in maximal aerobic capacity. 2) Improvements in other measured cardiovascular and metabolic parameters will occur in both young and elderly groups and will be proportional to the changes in aerobic capacity. Findings from these studies may ultimately help define the physiological and cellular responses to exercise training in the elderly. In the future it may be possible to restore lost responsiveness in aged target tissues by appropriate physiologic and biochemical manipulations.